Safety device for doorknor locks



Oct. 13, 1953 w. BIRBAUM SAFETY DEVICE FOR DOORKNOB LOCKS Filed May 5, 1950 INVENTOR. LESTER W. BIRBAUM ATTORNEY Patented Oct. 13, 1953 UNITED STATES PATENT o-FF 2,655,398 ICE FOR; DQOBKNQB LQGKQ Lester W, Birbanm, Oconomowoc, Wis-,, assignor to Belle Industries, Inc., ()conomqwoc Wis), a corporation oh Wisconsin l llg ifi tfim 5,, 19 0,; Serial Nut mane 5 Claims.

nvention lat a a sa e device which lzxer e s nenine a oorknob. 0; withoata sevi Doorknp ac are wel knew r dev ces w n the ea me han m. s. in he nob, its lf and se ep i e leek e knob, with re aectto he aid}, eratin strai ermits. he. nobq. rot-v ater with respect a he sh f I na, when. the door-is lockedgthe knobtrotates re l v an o eat. ita he shaft re y nrer nt ng: era: he f. he a en o. pen. t e, d n- The knob; p or ota es a ha sle a n ureemhe lien:- of; the shaft with the, lock, T e. sleeve is mt am with he knob) wit r p t v the e e fi s.- e sha t, s u y,v a slight; transv rse oad. o th knobt will ermit; he eve,- t tr nallr en ag he shaft. to. a1: 19in the kn ho rotat the haft yen. tho h. flocke Q1 e: t er-h d fit e fi betweenhe: leeve and he sham o o e, the. shaft; ql f ll etiqnr to th 9 k, mechanism is adversel affected, Therefore a. middle course allowimgqtut spme may? ilke fitis generall aken It P sible however o oact he im scumci n y a rictiena lr e a e he haft under. h e; nditi nsn T prin aal bj ctotth nvention. ist p o vide a safety device preventing operationof a, ,99 la ch it mo ai e," aeorkmh co a ni a a 0.0 me hanism hen: doors lo ked,

Another; bi ct s o rqvideadeviee o adoqtspohv ocktw ich-e yent ri i naln a ment; iw lse atch aeratin sh t Another. object, is; to"; provide a device, for a qee k oh q ls o tran mit transy rsel tomato, thedopr we thers b ect. s. to p o de at amaera t atdeyic ja r vent ng omr ta ionai move- 3 i, adoerlmob; o k th espect to the doorin ti lurth r, b ect a r y de. a attra tiYar seplate.

ther. bj cts a t dy n ee s l be minted l rea na en rom, the specific tiona a clajms as will obyious modificationsof the single eirl adiiaent t hqwnin thedraw aea n which:

F g, l is a side elevation with parts, bxokenaway of a doorknob ;1ock,an d} a conventional doorknob mounted on a door and provided with safety mee n preventing frictional engagement of the latch operating shaft when actuating the dooroa-lotla Fig. 2 is an exploded perspective, view of a conventional doorknob lock and the hub plate and rese plate employedto prevent sufllcient movement "of the knobto engage the shaft {and i Fig, 3-is:a section taken as indicated l.

Referring-tome drawingsindeta-il, Fig lvillustratesta conventionaldoorknom [0 containing :a lock-mounted on- -a door -I 2 and having latch opcrating shaft I} extendingthrough the hole I6 in the door for connect-ionto a' conventional doorofrthe holesn .in'thelfree endaofethe shafa The shaft. M operatesithe latch" ltintheeonvefltibnal manner. Thedoorlgnob: l'll contains alocle mQche anism whichwhen locked allows the knob rotate, freela wi h respect to. the; shaft IA and thereby prevent operation of. the latch the lock mechanism is unlocked the is locked withrespeet to. the: shaft 14 and may, therefore be turned ,toactuate, the shaft or crate the latchto; open. the door. 'llhetofn conventional knob; 18 is-not providedwith aloclc, mechanism and is, always,- operative to turn the shaft} It by virtue, of" its; connection to.- the. shaft} byv-meansjotscrew Z0; p

The. wellrk nownr lock mechanismwithiniknoh llisnotshownbuhmay be 05 thetype show-m l s Batent No. 1,903,190,, to .Stephen W. Neldnen dated; March-1 28, 1 933., fon example. As; may be seen. in Fig, 2,, the centen of theoutsidfi: face, knob, Ill providedzwith a: slot; zea ap dt e oeivetthetkey operating-theloolemechanisnn. may beseen inFigs. l: and 3, thetlatchaoperating shaft; I4 iasecuredt in: a cylindrical member. 282 which is vrotatably: supported I in and-r gu d d;- ll sleeve 30. Sleeve 30 is K-fixed; with respect;toiltnola l0 andmotates-therewith whilelteeping the shaft oriented with respect to the lock. As is conventional neclefllof knob: mlextends towardrthe door to abut roseplate 44L. Aswilltappeanherw matter rose; plate,- M isz not: of conventional-- de-- sign. Reference tolthe drawings showsvthat a; slightnlearanceisrprovided between sleeveutli theg cylindricalportionl 8 10f shaft M ThisioL-r lows1 preferred design practice in oallowing slight play: between the knobt and-the shaft, to r akevit; more; diflicultl to:- load the; knohvtransyersely to, causec the sleeve 30 to frictionall yv engage; the}: cylindrical portion. zasoflshaft; l4 therebyt permit; unauthorized; operation; of; the lateral The small annular space betweenthecsleeve: and-,the, cylindrical: portion of the. shaft 11012,, however, sufficient to, prevent frictional" engagea merits, of the shaft when the. knob is severely;

loaded; To, guard "against. such engagementl oft the shaft; the present" structure incorporateaa plate 34 having a cylindrical hub 36 adapted to snugly. receive "sleeve 30'. The n flat portion. 38 of thehnbhplafietis proyidejd with holes All.permittijnglv the; plate to. be secured ,to thedoor bf'y:. meansot. screws-42g Whenthe hubplate is se'curetiftoothe1. dOQ ,sleeye 30"Ican,rotate withinthethlibl. The. close fitjbjetwteen thehnb. and the sleveprevlents. w ea jnahe no i h re ct? to the do r a with respfectqto the latch operatingshaft'i transverse force ,appliiedlto knob; In'istransmitt (if to the-door; through thehuhplate: Thusit is impossibleto loadtheknob' ltfto cause thesleeve" 30" to f-rictionally engage the operating shaft *3 Ofl'oourse; the hub plate would afford littl-'- proteetiomifthe serewslt' were accessiblee With this inmind \provide a novel rose. plate ll- 'whicw presents smooth surface -and does not requin'e the conventional mountingscrews.- 'I his-mose platetis provided withan annular seat tportio'n estates 3 46 adapted to receive the end of neck 32. The inside wall 48 of the seat portion 46 is turned in slightly to present a generally frusto conical configuration. The inside diameter of the edge 49 of wall 48 is less than the outside diameter of the hub. With the wall 48 of rose plate 44 sprung in this manner, any attempt to remove the rose plate tends to cause edge 49 to bite into the hub plate. Therefore, when the rose plate is mounted as illustrated in Fig. 1 with its outer periphery flush against the door, it is substantially impossible to remove the rose plate Without complete destruction of the plate.

' Of course, the inside doorknob may be removed by loosening screw 28. After the inside knob l8 has been removed, the doorknob Hl may be withdrawn, if necessary. Rose plate 44 cannot be removed under any condition without destroying the rose plate. It will be appreciated by those familiar with the p ychology of those who tamper with locks that the necessity for such destruction substantially precludes tampering. The hub plate and the rose plate may be readily secured to the door by first removing the inside knob, Withdrawing the outside knob (and replacing it with a doorknob look if one is not already in use), centering the hub plate on the door and securing it thereto by means of screws 42, and then pressing rose plate 44 onto the hub. Shank l4 may now be inserted through the door and the inside knob secured thereto. It will be appreciated that the hub plate prevents the frictional engagement of the latch operating shaft l4 with the doorknob by transmitting to the door any forces applied to the knob transversely of the shaft. The function of the rose plate is to prevent tampering with the hub plate while presenting an attractive exterior. The' press fit employed between the rose plate and the hub plate renders it substantially impossible to tamper with the hub plate after it has been secured to the door. Itwill be appreciated that this simple sructure makes the doorknob lock tamper-proof. 7 Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope'of the appended claims.

I claim: 1. The combination with a doorknob of the type containing a lock mechanism for permitting rotation of the knob with or with respect to the latch operating shaft, said knob including a" sleeve coaxial with and surrounding said shaft, of safety means for preventing frictional engage-v 2. The combination with a doorknob of the type containing a lock mechanism for permitting rotation of the knob with or with respect to the latch operating shaft, said knob including a sleeve coaxial with and surrounding said shaft for supporting the shaft, said knob also including a cylindrical neck portion coaxial with the sleeve and spaced outwardly from the sleeve, of safety means for preventing frictional engagement of said shaftv and said sleeve when the knob is subjected'to a transverse force, said means comprising, a plate adapted to be secured to a door and including a cylindrical hub fitting snugly over said sleeve to transmit transverse forces from the knob to the door, and a dished centrally apertured rose plate having a press fit with said hub, the outer periphery of said rose plate being adapted to lie flush against the door to enclose and prevent access to said hub plate, said rose plate including an annular seat adapted to receive the end of said neck portion of said knob.

3. The combination with a doorknob of the type containing a lock mechanism for permitting rotation of the knob with or with respect to the latch operating shaft, said knob including a sleeve surrounding and coaxial with said shaft, of safety means for preventing rotation of said shaft by said knob when the knob is loaded transverse the shaft axis while being rotated and thereby frictionally engaging the shaft, said safety means comprising, a plate including a cylindrical hub snugly fitting over said sleeve and a flange adapted to be secured to a door, so that a transverse force on said knob will be transmitted through said hub plate to the door, and a centrally apertured rose plate having a press fit with said hub and being adapted to abut the sleeve surrounding and coaxial with said shaft,

of means engaging said sleeve exteriorly and adapted to be secured to a door to transmit transverse forces applied to the knob to the door, and means preventing access to said engaging means. 5. Apparatus for preventing lateral movement of a doorknob having a cylindrical shank, comprising, a hub plate adapted to be secured to a door and having a cylindrical hub portion adapted to snugly fit over a substantial portion of said cylindrical shank to transmit lateral forces from the knob to the door, and a centrally apertured dished rose plate having a press fit 'on said cylindrical hub portion of said hub plate and abutting said door to cover the hub plate and the means securing the hub plate to the door.

LESTER W. BIRBAUM.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,424,686 Somers Aug. 1, 1922 1,633,183 Koch et a1. June 21, 1927 1,653,513 Schlage Dec. 20, 1927 1,883,119 Toncray Oct. 18, 1932 2,104,403 Roethel Jan. 4. 1938 FOREIGN PATENTS Number Country Date 355,578 Germany June 30, 1922- 

